Issue 3668: Let NullVoice have an existence in MIDI

Issue 3457 omitted to introduce the NullVoice context into MIDI.  This
implementation is incomplete (see the TODO in performer-init.ly), but
at least it does not let the context structure go off the deep end in
MIDI.

diff --git a/ly/performer-init.ly b/ly/performer-init.ly
index 0a1ac2d3748e6de857e21e51b1d4801f8d6efe74..1a383607f1ea2c4d068edcf322f3cb5cf0ef2e6f 100644 (file)
--- a/ly/performer-init.ly
+++ b/ly/performer-init.ly
@@ -26,6 +26,7 @@
   \name Staff
   \accepts Voice
   \accepts CueVoice
+  \accepts NullVoice
   \defaultchild Voice
 
   \consists "Staff_performer"
@@ -181,6 +182,20 @@
   \name "Devnull"
 }
 
+\context {
+  \type "Performer_Group"
+  \name NullVoice
+  \alias Staff
+  \alias Voice
+  %% needed for melismata
+  %% TODO: at least the tie performer likely does not work without the
+  %% Note_performer, but I don't know how to shut note output off in
+  %% MIDI.
+  \consists "Tie_performer"
+  \consists "Beam_performer"
+  \consists "Slur_performer"
+}
+
 \context {
   \Staff
   \name TabStaff